Effect of Na2SiO3 and SDBS electrolyte additives on corrosion inhibition of zinc electrodes and electrochemical performance of zinc–air batteries

In order to alleviate the hydrogen evolution corrosion, passivation, and zinc dendrite growth during the charging and discharging of the zinc–bismuth negative electrode of zinc–air battery, the effects of the addition amounts of single Na2SiO3 and SDBS and their compounding on the corrosion inhibition effect and the charging and discharging performance of zinc–air battery in a new KOH-KF-K2CO3 electrolyte system were systematically investigated in this paper. In addition, the inhibition mechanisms of related inhibitors were discussed using FT-IR and XPS analyses. The results show that the addition of single Na2SiO3 and SDBS in the electrolyte can inhibit hydrogen evolution, dendrite formation, and passivation of the zinc electrode, thereby improving the charging/discharging performance of the battery, and the combination of Na2SiO3 and SDBS has a synergistic effect in improving corrosion inhibition and electrochemical performance of the electrode. When the additive concentration of the composite electrolyte is 1-g/L Na2SiO3 + 55-mg/L SDBS, the hydrogen evolution corrosion inhibition efficiency can reach 52.46%. Under the current density of 25 mA/cm2, the initial specific capacity and the capacity retention rate after the 300th cycle of the electrode can reach 523.5 mAh/g and 88.27%, respectively. It is found that both inhibitors can adsorb on the surface of zinc electrode in alkaline electrolyte to form a protective film on zinc electrode. The hydrogen evolution and corrosion inhibition effects of Na2SiO3 are better than SDBS, while the dendrite inhibition effect of SDBS is better than Na2SiO3. However, due to their different adsorption mechanisms, the compound addition can synergistically improve the coverage of the protective film, thereby inhibiting the corrosion, passivation, and dendrite of zinc electrode and effectively improve the first discharge specific capacity and cycle life of the battery.